Forty-six days of daily algorithm: Add binary (Binary Character addition)

Binary Character addition, Which is bit by bit. You can also abstract the process of addition into a function.

Given two binary strings, return their sum (also a binary string ).

For example,
A ="11"
B ="1"
Return"100".

Method 1:

class Solution {public:        string addBinary(string a, string b) {        int a_len=a.length();        int b_len=b.length();        if(a_len==0)            return b;        if(b_len==0)            return a;        string result="";        int max=(a_len>b_len?a_len:b_len);        int j=a_len-1;        int k=b_len-1;        int sum=0;        for(int i=0;i<max;i++,j--,k--)        {            if(j>=0)            {                sum+=a[j]-'0';            }            if(k>=0)                sum+=b[k]-'0';            result=(char)((sum&1)+'0')+result;            sum=sum>>1;        }        if(sum>0)            result='1'+result;        return result;        }};

Method 2:

// add a and b and carry, return a + b + carry.// carry will be updated when add char.char add_char(char a, char b, char &c){    if (a == b && a == '1')    {        char ret = c;        c = '1';        return ret;    }    else if (a == b && a == '0')    {        char ret = c;        c = '0';        return ret;    }    else    {        if (c == '1')        {            return '0';        }        else        {            return '1';        }    }} // Given two binary strings, return their sum (also a binary string).// For example,// a = "11"// b = "1"// Return "100".string add_binary(string a, string b) {    // Init result with the longest string.    string result = a.size() > b.size() ? a : b;    // Init carry with '0'.    char carry = '0';        const char *pa = a.data() + a.size() - 1;    const char *pb = b.data() + b.size() - 1;    string::iterator pc = result.begin() + result.size() - 1;        while (pa != a.data() - 1 || pb != b.data() - 1)    {        if (pa == a.data() - 1)        {            *pc-- = add_char('0', *pb--, carry);        }        else if (pb == b.data() - 1)        {            *pc-- = add_char(*pa--, '0', carry);        }        else        {            *pc-- = add_char(*pa--, *pb--, carry);        }    }        if (carry == '1')    {        return "1" + result;    }        return result;}

Forty-six days of daily algorithm: Add binary (Binary Character addition)